Subqueries can lead to filters not being applied

[floriankramer]

As mentioned in #156 by @niklas88:
Could this be related to the problem discussed on the list, that:

PREFIX wd: <http://www.wikidata.org/entity/>
PREFIX wdt: <http://www.wikidata.org/prop/direct/>
PREFIX wikibase: <http://wikiba.se/ontology#>
PREFIX schema: <http://schema.org/>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>

SELECT ?predicate ?predicate_name WHERE {
    ?x wikibase:claim ?predicate .
    ?x rdfs:label ?predicate_name .
    FILTER regex(?predicate_name, "^"occ") .
    FILTER langMatches(lang(?predicate_name), "en") 
}

works with prefix regex but adding a subquery fails to filter:

PREFIX wd: <http://www.wikidata.org/entity/>
PREFIX wdt: <http://www.wikidata.org/prop/direct/>
PREFIX wikibase: <http://wikiba.se/ontology#>
PREFIX schema: <http://schema.org/>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>

SELECT ?predicate ?predicate_name ?count WHERE {
    {
        SELECT ?predicate (COUNT(?predicate) as ?count) WHERE {
          ?person wdt:P31 wd:Q5 .
          ?person ql:has-predicate ?predicate
        }
        GROUP BY ?predicate
        ORDER BY DESC(?count)
    } 

    ?x wikibase:claim ?predicate .
    ?x rdfs:label ?predicate_name .
    FILTER regex(?predicate_name, "^"occ") .
    FILTER langMatches(lang(?predicate_name), "en") 
}

If you don't think this is the same issue I'll open a separate one

[niklas88]

Note that FILTER regex(?predicate_name, "^"occ") . is also a problem with the parser because the correct FILTER regex(?predicate_name, "^\"occ") . form isn't supported